Date of Award

Spring 1-1-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology & Evolutionary Biology

First Advisor

Robert P. Guralnick

Second Advisor

Deane Bowers

Third Advisor

Andrew Martin

Fourth Advisor

Francois G. Meyer

Fifth Advisor

César Nufio

Abstract

Many species of parasitoid insects find their hosts by “eavesdropping” on the communication signals of other insects. Eavesdropping parasitoids are abundant and taxonomically diverse, but relatively little is known about the ecology and evolution of eavesdropping as a host-finding strategy. Furthermore, most such research has focused on a very small number of comparatively well-studied species. For my dissertation research, I developed a new eavesdropping parasitoid study system, and I used this system to investigate several key questions about the ecology and evolution of eavesdropping parasitoids in general. Specifically, I studied the parasitoid fly Emblemasoma erro (Diptera: Sarcophagidae), as well as other species of Emblemasoma, all of which eavesdrop on the acoustic mating calls of their cicada hosts (Hemiptera: Cicadidae). First, I demonstrated that E. erro is, in fact, an eavesdropping parasitoid, and I provided the first detailed descriptions of the life history, infection behavior, and host parasitism rates of this species. Next, I investigated the role of male hearing in E. erro. I found that both male and female E. erro use the calls of their hosts to locate mates, which is the first known example of intraspecific acoustic eavesdropping for the purpose of mate finding. With a third set of experiments, I investigated the signal preferences and host range of E. erro. I discovered that, unlike some other acoustic parasitoids, E. erro can exploit a large number of host species by listening for acoustic signal characteristics that are not species-specific. Fourth, through a variety of laboratory and field experiments, I demonstrated that larval E. erro avoid intraspecific competition by altering the mating calls of their host cicadas. These call changes make parasitized hosts much less likely to be discovered, and superparasitized, by foraging female E. erro. Finally, I used multi-locus DNA sequence data from many sarcophagid species, including multiple species of Emblemasoma, to reconstruct the phylogeny of Sarcophagidae. I then inferred the evolution of feeding behaviors in this ecologically diverse family of flies and confirmed that hearing, which is only found in Emblemasoma, most likely evolved in response to the selective pressure of parasitoid host finding.

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